Amines, such as amine catalysts that are useful in the polyurethane industry, may degrade over time or upon exposure to air. As the amines degrade, undesirable products such as formaldehyde and dimethylformamide (DMF), or both are produced. For instance, formaldehyde may be formed by oxidative demethylation of an amine and DMF may be obtained from certain tertiary amines by a similar oxidation process as is shown in FIG. 1. Formaldehyde and/or DMF from the amine may then be inadvertently incorporated into polyurethane or polyisocyanurate formulations and hence into the product of the formulation. Such products include insulation for buildings and appliances; flexible foams for beds, other furniture, and automobile seats; elastomers such as shoe soles, skate wheels, medical elastomers, and the like; urethane and/or urea coatings; and high-modulus urethane plastics such as furniture foam, molded doors, and rigid insulation panels just to name a few end products.
Both formaldehyde and DMF are linked to human health risks. Formaldehyde is a common indoor pollutant and may be toxic. Furthermore, it may cause allergic reactions in formaldehyde-sensitive people and it may be a human carcinogen. DMF is a possible carcinogen and is believed to cause birth defects. Thus, exposure to formaldehyde and DMF should be limited. Current short-term exposure limits, such as 15 minutes, for DMF and formaldehyde are 20 parts per million (ppm) and 2 ppm respectively and longer permissible exposure limits, such as eight hours, for DMF and formaldehyde are 10 ppm and 0.75 ppm respectively, as determined by the Occupational Safety and Health Administration (OSHA).
Depending upon the age of an oxidation-sensitive amine, DMF and formaldehyde may be found in relatively high amounts. Thus, there is a need for reduced concentrations of DMF and/or formaldehyde in oxidation-sensitive amines.